It was a figure of language, certainly, in the sense of contrasting the way people let pass an elephant and filter a mosquito. So, to people at the time understand with no shadow of a doubt the exageration was used. In our day-to-day sometimes we do that, we correct the slightest dust at home (to wife/hubby or he who stays home: what did you do all day?) and say nothing to the boss that have his desk a mess, things scattered, no one could find anything there, but guess what? we pretend it is neatly arranged!